1. Field of the Invention
The invention relates to a technique of controlling hydraulic pressure to an engagement element.
2. Description of Related Art
Among vehicles that have plural engagement elements and a solenoid valve for selecting supply/discharge of hydraulic pressure to/from these engagement elements and in which the hydraulic pressure is supplied to this solenoid valve, a vehicle that includes an economic running system for automatically stopping an engine when a specified economic running condition related to an engine operation state or a vehicle travel state is established has been well known.
For example, an oil pump is provided in a torque converter in a vehicle described in Japanese Patent Application Publication No. 11-013787 (JP 11-013787 A). When the specified economic running condition is established, the engine is automatically stopped, and thus an engine speed is reduced. In conjunction with this, an amount of the hydraulic pressure that is supplied from the oil pump to the engagement elements is reduced.